Propeller.



N. H. FREEMAN. ROPBLLER.

APPLICATION FILED 00T. 26, 1911.

Patented Jai-7,1913.

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, UNITED STATES PATENT OFFICE l e EAT H. FREEMAN, or DENVER, cOLORAiJo6 d :PEOPELLERb Y. i

Speccation of Letters Batent.

To all whom z' may concern:

' Be it known thatV I, NAT H. FREEMAN a citizen of the United States, residing in the city and county Of yDenver and State of Colorado, have invented certainvnewand Vuseful Improvements-in Propellers; andl do declare the following tokbe a full, clear, and exact description of the invention, such as will enable others skilled` in theart to which it appertainsto make and use the same, reference beinghad to the accompanying drawings,and to the Characters of reference marked' thereon, -which form a part of this specification.`

My invention relates to'improvements in propellers, more especially intendedfor use in connectionwith flyingY machines, my 0bject being to provide `ajdevice of this char-` acter which shall prevent` what may be` j termed the atmospheric slip or escapeof the air laterally from the bladesvin a direction away from the `z one of rotation. The

tendency, in propellers of this character, as ordinarily constructed, is to drive all of the air out of the zone ofrotation, thus pro-v ducing a partial vacuum in the atmosphere and, to a large extent, removing the resist` ance upon which'the propeller blades must rely for effective operation.y i f The ldiiiiculty of flying with heavier than air machines is, of course, due to the fact o-f the lack of density of the atmospheric` medium; otherwise, it would be as easy to navigate the air as the water, the difference between traveling in ornpon the twov mediums being entirely dueL to the difference in density. Thevordinary propeller with fiat blades, inclined in the well known manner,

as soonas it begins to rotate, forces the air strongly radially in all directions from the axis of rotation, thus having a tendency to drive the air or resist-ingy medium out of suchv zone, the result being either the production of a vacuum or the rarefaction of the air to such an extent that it is of little or no avail as a resisting medium. The more rapidly the propeller rotates the greater is the tendency to producethe aforesaid result.

Various e'orts have beenmade to overcome this. dificulty, the mechanisms employed `be-l.

ingV generally quite complicated and" consehandle, and, therefore,

My -improved propeller, as hereinafter eX- plained,' is exceedingly simple in construcying' bends therein, from the airis in Operation.

sists in\forming the y' propeller' bladesv off. relatively thin sheet. metal and forme f increasing in l depth]` Generally speaking, my improvement conn Patente/d Jan.7,f19'13. AApplicationfuse october 2e, 1911.r serial Nb. 656,994.. y

of` krotation outwardly,

the said bends preventing the ,atmos-,jV

pherie slip, or lateral escape of the" airy as-1t 1s acted upon by the blades.k To fur-f` ther increasethe efliciency of my improved,

construction, the blades are deflected in,-

wardly from a direction at right angles` to theaXis of rotation, the inward deflection;

kbeing in a rearward direction, assuming that themachineywith which the propellerV is connected is traveling in a horizontal plane, thus having Va tendency, not only to prevent the air from passing out Of the zone of rotation, but alsoy driving it` inwardly toward ythe axis, thus further Aincreasing' its eiciency as a resisting medium.V l Having briey outlined my improved construction, I will proceed tode'scribe the` same inrdetail, reference being made tothe accompanying drawing, in which is'illus-V trated an embodiment thereof.

VIn this drawing: Figure 1 is a top"k planf view Ofwmyuimproved propeller, assuming that'the aXis yof rotation is in a horizontal position. Fig.,2 is a rear view of the same, Or a view looking inthe direction of arrow 2, Fig. y1. y i

The same reference characters indicate the same parts inall the views.

Let the numeral 5 designate a shaft upon which myimproved propeller 6 is mounted to rotate in the direction indicated by arrow- 7.`- As illustrated in the drawing, the propeller consists of a. hubS, towhich are ksecured' inany suitable manner'two `blades 9," f a which are of the same construction, whereby the propeller is properly balanced; ,AsfilluS-f trated inthe drawing, theblades are formed integral with the hub 8. It is evident, hown ever, that they may be connected therewith in any suit-able manner. 4These propeller blades are each provided with bends A, B, C, and D, the bend A 4being somewhatless in depth than the bend- B, while the bend C is of greater depth than the bend B, and' thek bend D of greatestdepth.- Thisconstruction of blade is formed by bending the'biade alternately in opposite directions,the outer" orfree extremity 10 of the blade extending 110 beyond the bend C. It may be assumed that, before the bends A, B, C and D are formed in each blade, the blade is inclined in such a manner as to perform the proper function in the manner of the usual or ordinaryY propeller blade. The blade, wit-hout changing its inclination, is formed into the bends, as aforesaid, and, in order to maintain each blade in the bent position, a rod 12 is passed through the blade in a lengthwise direction, the said rod crossing the bends some distance beyond the arch of each. The inner eX- tremity of each rod, as illustrated in the drawing, is anchored in the hub of the propeller, as shown at 13. At each place, where the rod 12 passes through the propeller blade, nuts 14 are applied to the rod, which is threaded for the purpose. These nuts form stops to prevent any tendency on the part of the blade to straighten out or neutralize the bends formed therein for the purpose stated.

During the operation of the propeller, the bends prevent the atmospheric slip in a direction outwardly from the aXis of rotation, and this result is increased by virtue of the increase in the depth of the bends from the inner extremities of the blades out wardly. For instance, the air which slips from the surface 15 of the bend A may travel in a direction outwardly from the axis of rotation, but this air will strike the surface of the bend B, which forms a stop against its further travel in an outward direction; while the air which slips from the surface 17 of the bend C will strike the inner surface 18 of the member 10 of the bend D. The result will be that the air will be directed rearwardly and inwardly toward the axis of rotation, as indicated by the arrows 19.

Having thus described my invention, what I claim is 1. A propeller equipped with blades, which are inclined to the plane of the axis of rotation and increase in width from the said aXis outwardly, the blades being bent transversely to form a number of corrugations, and rods passed through the blades in a longitudinal direction, the rods being threaded and equipped with nuts engaging the blades to lock the latter against any tendency to straighten or neutralize the bends when in operation, substantially as described. 1

2. A propeller equipped with blades bent transversely to form a number of corrugations, rods passed through the blades in alongitudinal direction, the rods being threaded and equipped with nuts engaging the blades to lock the latter against any tendency to straighten or neutralize the bends when in operation, substantially as described.

In testimony whereof I aiiiX my signature in presence of two witnesses.

NAT H. FREEMAN.

Witnesses A. J. OBRIEN, F. E. BOWEN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

